Welcome to the LEES Lab
The LEES Lab at the CGCEO of Michigan State University, directed by
Dr.Jiquan Chen, is interested in scientific investigations and education on
fundamental ecosystem and landscape processes for understanding ecosystem
functions and management.
Our current studies are focused on the carbon and water cycles of
different ecosystems (grassland, desert, forest, cropland, wetlands,
freshwater) at multiple spatial and
temporal scales, bioenergy systems and resource uses, coupled interactions
and feedback between climatic change and human activities, and sustainable
management and conservation.
Our research projects, spreading mostly across North American and
Asian landscapes, are based on sound field experiments and monitoring
stations, state-of-the-art equipment and technology, modeling, and remote
sensing technology. The LEES Lab is also the home of book series on
"Ecosystem Science and Applications—ESA" for the Higher Education Press
(HEP) and De Gruyter. We maintain a high ethical and liberal standard for professional collaborations in research and education.
Multiple Resource Use Efficiency (mRUE): A New Concept for Ecosystem Production
Juanjuan Han, Jiquan Chen, Yuan Miao & Shiqiang Wan
The resource-driven concept, which is an important school for investigating ecosystem production, has been applied for decades. However, the regulatory mechanisms of production by multiple resources remain unclear. We formulated a new algorithm model that integrates multiple resource uses to study ecosystem production and tested its applications on a water-availability gradient in semi-arid grassland. The result of our experiment showed that changes in water availability significantly affected the resources of light and nitrogen, and altered the relationships among multiple resource absorption rate (ε), multiple resource use efficiency (mRUE), and available resource (Ravail).
The increased water availability suppressed ecosystem mRUE (i.e., "declining marginal returns"); The changes in mRUE had a negative effect on ε (i.e., "inverse feedback"). These two processes jointly regulated that the stimulated single resource availability would promote ecosystem production rather than suppress it, even when mRUE was reduced. This study illustrated the use of the mRUE model in exploring the coherent relationships among the key parameters on regulating the ecosystem production for future modeling, and evaluated the sensitivity of this conceptual model under different dataset properties. However, this model needs extensive validation by the ecological community before it can extrapolate this method to other ecosystems in the future.
Figure: The conceptual framework of this study.
Within the matrix of the bio-physical environment (microclimate and disturbance), the magnitude of aboveground net primary productivity (ANPP) is determined by the resource use matrix of [ε, mRUE, Ravail] and their complex interactions. For each type of resource, there exists complex interactions among [ε, mRUE, Ravail] at various temporal scales. Alteration of any element of the resource use matrix will trigger changes in other elements. This study will examine the feedbacks among the elements, with a focus on water, light, and nitrogen.